In communication technology, specifically electrical or optical transmission technology, communication modules are used to process very large quantities of data. This causes the circuits arranged on the communication modules to become very hot. This effect is further heightened by the high density with which the circuits are arranged on such communication modules. The heat dissipation specifications for such communication modules therefore have to be very stringent. The dense arrangement of such communication modules means that fires can also result within a module holder. Other possible causes of fires are short circuits due to production or service errors and circuit overloads.
A number of module holders are generally integrated in one module rack that comprises two closed side walls, connected together by means of at least one upper and lower frame element and having at least one front door for example. To prevent heat building up within the respective module holder or subrack of the rack and fire resulting, fan units are provided in the module rack.
For module racks that comply with the requirements of the US standard NEBS for example such fan modules are integrated in both the base and the top surface of the module rack. Also—as already known from the German utility model document with the official reference DE 298 13 442 U1 for example—a fan module comprising a number of fans is provided on the top surface of a module holder, so that the heat energy resulting within the module holder can quickly be dissipated. Also a perforated plate slide-in module made of aluminum can for example be provided over the module holder, ensuring regular heat distribution within the module holder in the event of a fire.